We propose to characterize a newly discovered pigment which mediates active sodium transport in Halobacterium halobium in the presence of light. We are especially interested in probing this pigment by flash kinetic, low temperature absorption and resonance Raman spectroscopy to describe its various energetic states after photon excitation. We also intend to isolate the new pigment. Flash spectroscopy will be used as a convenient detection method for the presence of a functional pigment during its purification. Enriched or purified pigment fractions will then be chemically characterized according to established methodology for the study of retinal chromoproteins. Incorporation of the pigment into reconstituted model systems will be used to establish the functional role of the pigment.